Montan wax, also known as lignite wax, LP wax and/or S wax, is a hard wax obtained by solvent extraction of lignite or brown coal (sub-bituminous coal). As it has been preserved in the coal, it is really fossilized plant wax. The earliest production on a commercial scale was in Germany during the latter half of the nineteenth century, and Germany continues to supply the majority of the world's production of montan wax. The composition of montan wax depends on the material from which it is extracted, but all contain varying amounts of wax, resin, and asphalt. Resins must be removed by extraction with solvents (diethyl ether, acetone). The wax component of montan is a mixture of long chain (C24-C30) esters (62-68 wt %), long-chain acids (22-26 wt %), and long chain alcohols, ketones, and hydrocarbons (7-15 wt %). Montan has to go through an extensive chromic acid treatment to be refined, which process, for example, had been banned in California.
Montan wax is hard and brittle and has a high melt point; its properties are similar to those of natural plant waxes such as carnauba, which it can replace. Carbon papers were the largest consumer of crude montan wax. Currently the highest use of montan wax is in car polishes (30%). Additional applications include shoe polishes, electrical insulators, and lubricants in plastics and paper industry. Montan wax in polishes improves scuff resistance, increases water repellence, and imparts high gloss. Depending on refining and derivatization, waxes with different properties can be obtained from montan wax. Because montan wax is extracted from brown coal, the crude wax requires extensive and costly cleaning. Recently the concentration of extractable montan wax in the German rock formations has decreased. Due to the uncertainty of supply and varying nature of the product, as well as its relative high cost, a substitute for montan wax having similar properties to montan wax is desirable.
Carnauba wax is derived from the palm tree, whose wax-producing stands grow almost exclusively in the semiarid northeast section of Brazil. Carnauba wax forms on the fronds of the palm, and is removed by cutting the fronds, drying, and mechanically removing the wax. Impurities are removed from the wax by melting and filtering or centrifuging. Wide fluctuations in price and availability have caused markets served by carnauba wax to seek replacements. The major components of carnauba wax are aliphatic and aromatic esters of long-chain alcohols and acids, with smaller amounts of free fatty acids and alcohols, and resins. Carnauba wax is very hard, with a penetration of 2 dmm at 25° C. and only 3 dmm at 43.3° C. Certain grades of carnauba wax may also have one of the higher melting points for the natural waxes. For example, one grade of carnauba wax has a melting point of 84° C., with a viscosity of 3960 cSt at 98.9° C., an acid number of 8, and a saponification number of 80.
The hardness and high melting point, when combined with its ability to disperse pigments such as carbon black, allows Carnauba wax increasing use in the thermal printing inks. Carnauba wax is also widely used as organic structurant to gel organic solvents and oils, making the wax a valuable component of solvent and oil paste formulations. Carnauba wax polishes to a high gloss and thus is widely used as a polishing agent for items such as leather, candies, and pills. Other uses include cosmetics and investment casting applications (e.g., copper alloys, cast copper alloys).
Candelilla wax is harvested from shrubs in the Mexican states of Coahuila and Chihuahua and, to a very small degree, in the Big Bend region of Texas in the United States. The entire mature plant is uprooted and immersed in boiling water acidified with sulfuric acid. The wax floats to the surface and is filtered. The major components of candelilla wax are hydrocarbons, esters of long-chain alcohols and acids, long-chain alcohols, sterols, and neutral resins, and long-chain acids. Typically, candelilla wax has a melting point of 70° C., a penetration of 3 dmm at 25° C., an acid number of 14, and a saponification number of 55. Principal markets for Candelilla include cosmetics, foods, and pharmaceuticals.
Japan wax is a fat and is derived from the berries of a small tree native to Japan and China cultivated for its wax. Japan wax is composed of triglycerides, primarily tripalmitin. Japan wax typically has a melting point of 53° C., an acid number of 18, and a saponification number of 217. Principal markets include the formulation of candles, polishes, lubricants, and as an additive to thermoplastic resins. The product has some food-related applications.
Ouricury wax is a brown wax obtained from the fronds of a palm tree, which grows in Brazil. Ouricury is difficult to harvest, as it does not flake off the frond as does carnauba wax and must be scraped off. Ouricury is sometimes used as a replacement for carnauba in applications that do not require a light-colored wax. Rice-bran wax is extracted from crude rice-bran oil. It can be degummed, the fatty acid content reduced by solvent extraction, and bleached. The wax is primarily composed of esters of lignoceric acid (43 wt %), behenic acid (16 wt %), and C22-C36 alcohols (28 wt %).
There is a need for a natural oil fatty acid wax that may completely substitute and/or replace other waxes, such as those identified above, or may be used as an extender for such waxes.